"Grand Theft Auto IV” marks a huge leap forward for videogames as an immersive experience while making little more than a few tweaks to the ultra-successful franchise's formula.

“Grand Theft Auto IV” marks a huge leap forward for videogames as an immersive experience while making little more than a few tweaks to the ultra-successful franchise’s formula. The technological prowess and artistic detail are so phenomenal and the sheer amount of content is so staggeringly deep that players will find themselves drawn into Liberty City like no other fictional place. Such deep immersion sometimes highlights the flaws in “Grand Theft Auto’s” well-worn formula, but that will be little more than an asterisk for the millions of gamers sure to be carjacking their way through “GTA IV” for a long, long time to come.

Like the last few “GTA” installments, the game follows a tough-as-nails newcomer working his way up in a city full of crazy characters, sexy women and endless opportunities to cause mayhem. The game opens with a man getting off a boat in Liberty City, a significantly downsized but amazingly lifelike replica of New York. Protagonist Niko Bellic, who’s succinctly described as “a drug dealing de-fucking-generate from some armpit in Eastern Europe,” is in town to start a new life and, players slowly discover, make up for sins in his past.

But while Niko is the only fresh-faced foreigner in the game, the ideal of the American Dream that immigrants represent is the theme that runs through it. Every character in “GTA IV” is hustling and scheming for that elusive success that’s always just out of their grasp. “One day,” Niko’s cousin Roman vows at one point, “I’ll find that shortcut to the top.”

While Niko speaks primarily with his fists and weapons, he’s surrounded by the funniest cast of characters this side of “The Office.” From the delusional Roman, who’s convinced success is his before it arrives, to Brucie, a crazy steroid junkie with a bad habit of bashing his head into walls, to the media-savvy Manny, who boasts to his personal cameraman about how he’s saving South Bronx while Niko does his dirty work, they all create a living, breathing and surprisingly hilarious world. Though the stiff animation in the game’s frequent pre-animated cut scenes serves them poorly, writers Dan Houser and Rupert Humphries demonstrate that, unlike most videogame writers, they understand that a good story starts with great characters.

The “GTA” series fundamentally altered the videogame world years ago by creating a huge open world that players could explore at their own pace with no loading times. “GTA IV” ups the ante by rendering it all in hi-def with extreme detail and barely any technical glitches. All of New York’s major landmarks, like Central Park, the Empire State Building and JFK Airport, are present, as are local touches in every neighborhood. Even more astounding, however, is that Liberty City is a living, breathing city. Early morning in the South Bronx is marked by garbage trucks on their routes, junky cars parked on the side of the road, and homeless men huddled over makeshift fires, while afternoon Manhattan is a morass of sharply dressed business folks and luxury cars stuck in traffic.

Playing through the main story could easily take 40 hours, but there’s a virtually unlimited amount of game for those who want to explore every bar, every comedy club — and every hooker. (The game is rated M for a reason.)

Like other “GTA” games, there’s a broad array of radio stations to tune in to while driving, but “GTA IV” also boasts a cell phone that Niko uses to contact friends and set appointments, as well as computers for him to check email and surf the Web. The scope of it all is impressive, though much of the original content, most of it parody, flops. Rockstar’s attempts at humor are so on-the-nose and crudely left-wing — the Fox News-esque “Weasel News” reports that “Congress has renewed and extended the Jingoism Act” and ads tout “America’s Next Top Hooker” — that media-savvy players will be left groaning at the parade of lame jokes.

“GTA IV’s” only fundamental problem, however, is that the world and the story have advanced so far past the gameplay. The ability to go anywhere and do anything was revolutionary in the early “GTA” titles, but sometimes feels awkward in a game with such well-crafted characters and stories. How can players seriously believe Niko’s on a date when his girlfriend doesn’t mind that he’s carrying a knife, walking her through a 5-foot-deep pond and getting in numerous car accidents? Why can a distinctive-looking illegal immigrant commit hundreds of carjackings and nobody seems to care? There are good gameplay-related answers, of course, but they still detract from the immersive realism that “GTA IV” otherwise creates.

The one major change in the formula is in multiplayer, as “GTA IV” brings the series online for the first time. Most of the 14 modes are killing, chasing or racing competitions that experienced gamers have seen before. The difference is that “GTA IV” doesn’t limit multiplayer to a small map, but opens it up to an entire borough or even the whole city. Starting a 16-person match by the Statue of Liberty and ending it, after a thrilling helicopter ride, atop a Manhattan skyscraper is a wondrous integration of “GTA’s” open world ethos into the previously constrained world of online videogame play.

Grand Theft Auto IV

Rated M. $60.

Production

A Rockstar Games presentation of a game developed by Rockstar North for the Playstation 3 and Xbox 360. Reviewed on Xbox 360.